A bomb blast Monday killed eight people and injured at least 12 others at a medical school in Kano, Nigeria, the city's police commissioner said.

The explosive devices went off around 2 p.m. local time in a parking lot at the School of Hygiene, said Adelere Shinaba,police commissioner of Kano, Nigeria's second-largest city.

A suspect is in custody after being arrested on the scene, police said, and the suspect's car was discovered outside the school.

Police said they don't have a motive for the blast and are still investigating, but Boko Haram terrorists have targeted the northern Nigerian city in the past. The militant group says its aim is to impose a stricter enforcement of Sharia law across Nigeria, which is split between a majority Muslim north and a mostly Christian south.